The way people purchase games has changed a lot over the years. It used to be that we bought games for a flat fee upon their completion. Then we bought incomplete games at a reduced price so we could play them in their early stages, offer feedback, and get a sweet deal on the finished product. And now Anomaly: Warzone Earth developer 11 Bit Studios is bucking the trend - and possibly starting a new one - by allowing players a killer 50 per cent off deal on its next game with one small catch: the game hasn't been announced yet and no one knows what it is.

Here's what we do know: It will be released on PC, Mac and Linux via Steam for an estimated release sometime during Q2 2013; it will go into a multiplayer beta in late March and early adopters will gain access to this closed beta; players who pre-order will receive a "mysterious gaming gift" from 11 Bit; and the final game will cost $15, meaning pre-orders before the reveal will secure it for $7.50.

The new game will be announced on 28th February, at which point this half-off offer will be off the table. Until then, here's a teaser hinting at this top-secret title.

"Please note it's not a Kickstarter," said 11 Bit senior writer Paweł Miechowski in an exchange with Eurogamer. "I don't want to ask people for financial help, I'm just offering something hopefully intriguing enough and a gaming gift on the release day. If one does not want to get secret game, it is all fine, we will unveil it on Feb 28 anyway."

Miechowski noted that he was surprised at how well pre-orders have been going, though he didn't expect "a bazillion" of them.

As far as feedback to this experiment goes, Miechowski stated, "I was ready for negative comments, just because they are always there whatever you do in the internet. Some people behave kinda funny acting like we'd brutally force them to pre-order."

"If you're not sure whether you're willing to pay for the game, we ask that you please just wait until we actually announce it," he stated on 11 Bit's official site. "Sure, you'll pay full price, but this deal is for those brave souls who are willing to jump into the abyss with us and take a chance on a mystery."

In the years following the invasion of Earth in 2018, the planet is overrun by alien machines. Humankind is on the verge of extinction. Banded together in huge convoys, they search the frozen tundra for food and supplies. Since the war, the roles have been reversed: now our species seems to be the Anomaly on a machine-controlled planet. Your convoy, Commander, is called Yukon.

Anomaly 2 is a real-time strategy game that takes the tower offense concept from Anomaly Warzone Earth to a new level. Maintaining the core concepts of the original – tactical planning and the on-field Commander to support troops in combat – Anomaly 2 introduces a number of important new features:

- Morph your troops into war mechs to discover the new face of strategy: each unit has a different mech form with various abilities to help you overcome specific combat situations.

- Engage in a multiplayer experience unique to Anomaly 2: tower defense vs. tower offense. Play as the towers and destroy the humans or lead the humans to annihilate the alien towers.

- Fight across a post-apocalyptic world in a new single-player campaign that offers a more intense strategy experience than the acclaimed original.

- Carve your own path to victory and create your ultimate battle squad. With over million tactical combinations to build your squad, your options in combat are nearly endless.

- Dive into a beautifully rendered world, thanks to the team’s new and improved visual engine: